This invention relates to a shutter device, and more particularly, to a vacuum compatible fast shutter device that is suited for controlling a beam of radiation in photolithographic equipment used in the manufacture of integrated circuits.
In general lithography refers to processes for pattern transfer between various media. Projection lithography is a powerful and essential tool for microelectronics processing. FIG. 4 schematically depicts an apparatus for EUV lithography that comprises a radiation source 21, such as a synchrotron or a laser plasma source, that emits x-rays 22 into condenser 13 which in turn emits beam of light 14 that illuminates a portion of reticle or mask 15. The emerging patterned beam is introduced into the imaging optics 16 which projects an image of mask 15, shown mounted on mask stage 17, onto wafer 18 which is mounted on stage 19. Element 20, an x-y scanner, scans mask 15 and wafer 18 in such direction and at such relative speed as to accommodate the desired mask-to-image reduction. It may be necessary to shutter the radiation at various positions along the optical path(s) of the radiation. Mechanisms must be in place in the projection lithography system to accomplished this precisely and quickly for a light beam with a large footprint.
The present invention is directed to an in-vacuum exposure shutter that is capable of shuttering a large footprint light beam in a short time in a vacuum environment. The in-vacuum exposure shutter can be employed in any process or product that requires precise temporal control over a large footprint light beam.
In one aspect, the invention is directed to an exposure device that includes:
a source of radiation that generates an energy beam;
a shutter that includes (i) a frame defining an aperture toward which the energy beam is directed and (ii) a plurality of blades that are secured to the frame; and
means for rotating the shutter to cause the plurality of blades to intercept or allow the energy beam to travel through the aperture.
In one embodiment, each blade has a substantially planar surface and the plurality of blades are secured to the frame such that the planar surfaces of the plurality of blades are substantially parallel to each other. The exposure device is particularly suited for operation in a vacuum environment and can achieve shuttering time from about 0.1 second to 0.001 second or shorter.